Wide angle sweep yoke assembly



Aug. 21, 1951 c. E. TORSCH 2,565,331

WIDE ANGLE SWEEP YOKE ASSEMBLY Filed March 22, 1950 :5 shets-sheet 1 Ihv ntor= Charles E.Torsch,

u| His Attorney 1951 c. E. TORSCH 2,565,331

WIDE ANGLE SWEEP YOKE ASSEMBLY Filed March 22, 1950 3 Sheets-Sheet 2 Figll.

Inventor; Charles E.Tor"sch,

His Attorney.

Aug. 21, 1951 TQRSCH 2,565,331

WIDE ANGLE SWEEP YOKE ASSEMBLY Filed March 22, 1950 3 Sheets-Sheet 5 Inventor: Charles E.Torsch,

His Attorney.

Patented Aug. 21, 1951 wmn ANGLE swans YOKE AssmmLY Charles E. Touch, North Syracuse, N. Y, assignor to General Electric Company, a corporation of New Yolk Application March 22, 195., Serial No. 151,189

China. (Cl. 313-76) My invention relates to the construction and manufacture of a sweep'yoke assembly for the horizontal and vertical deflecting circuits of a cathode ray tube. It has particular application to an assembly adapted for operation with socalled wide angle tubes, in which the cathode ray may be deflected over a maximum angle of 70 or more.

My prior Patent 2,428,947. issued October 14, 194'], discloses a sweep yoke assembly in which high efliciency is obtained by employing interlocked pairs of horizontal and vertical deflecting coils of saddle shape." In this construction, the straight sides of the coils are coplanar so that they form a nearly complete, thin-walled cylinder which may closely surround the cylindrical neck portion of the cathode ray tube. The curved end sections of the coils are bent at substantially 90 to the axis of the assembly, and the coils of one pair have shorter axial lengths than the coils of the other pair, in order to permit the coil ends to cross over each other as required. Therefore, the straight sides of the shorter pair of coils should have somewhat greater cross-sections than the sides of the other pair, in order to equalize the effect of the greater eifective lengths of the latter.

The construction shown and described in my aforesaid patent has been found to provide satisfactory operation in conjunction with cathode ray tubes having ray deflection angles of 60" or more. However, certain limitations are encountered as the deflection angle is increased to 70 or more. Unless the eflective center of deflection of each pair of coils is located reasonably close to the apex of the angle subtended by the flared bulb portion of the tube, the cathode ray may strike the side walls of the bulb at maximum deflection angles, giving rise to what is commonly known as "neck shadow." Wide angle tubes, therefore, require deflecting coils of shorter effective axial lengths. Also, the lengths of both pairs of coils should be as nearly equal as possible to preserve the highest possible sensitivity of the necessarily shorter coils.

In addition, the surfaces of the coil ends adjacent the flared bulb portion of the tube should conform closely to the curvature thereof to minimize total coil inductance and cross-tm'n losses.

At first glance, these requirements appear to be almost impossible of fulfillment, because the outwardly-bent, curved coil ends of one pair must overlie the ends of the other pair. Hence, it has heretofore been thought that the axial lengthofthispairof coilsmustbe substantially 2 greater than. that of the other pair. However, in accordance with the present invention, I have found it possible to provide a construction which satisfies these requirements for all practical purposes.

Of course, it is possible to have all deflecting coils of the same axial length, and short enough for use with wide angle deflection tubes, if a co-axial (but non-coplanar) coil arrangement is employed rather than the interlocked, coplanar arrangement of my Patent 2,428,947. 0n the other hand, this has the serious disadvantage of requiring substantially greater driving power for both pairs of coils, in order to obtain the same ray deflection, because the effective deflecting field varies inversely with the square of the effective diameters of the coils. Thus, such a noncoplanar construction inherently requires a substantially greater volume of copper in the deflecting coils and substantially greater driving power, with lower efliciency. v

It is, therefore, a. primary object of my invention to provide an improved coplanar deflection yoke assembly for wide angle cathode ray tubes such as are employed in television receivers.

Another object of my invention is to provide a wide angle sweep yoke assembly employing interlocked, coplanar deflecting coils in which all coils may have substantially equal axial lengths, may surround the cylindrical neck portion of the cathode ray tube as closely as possible, and may fit against the flared bulb portion of the tube with a minimum of lost space.

Briefly, in a preferred form of my invention, these objects are achieved by so forming the pairs of deflecting coils that their outwardly-bent, curved ends are symmetrical in each pair and so that their straight portions have substantially equal lengths, thickness, and complementary circumierential spans. This is made possible by so shaping the coil ends as to have complementary interfitting, inclined surfaces which are closely contiguous to each other over substantially their entire areas of crossing contact. Finally, the inner surfaces of the innermost pair of coils are preferably tapered so as to conform very closely to the flare angle of the cathode ray tube.

In order to permit the coils to be closely interfltted in this manner, their shapes and dimensions must be held to very close tolerances in manufacture. In the past, it has been common practice to form the coils in approximately rectangular shape, or to shape them only roughly to the required dimensions, and then to form them to exact shape between blocking dies. However, the use of such dies is undesirable because of the danger that the die edges may damage the insulation or shear the fine wire strands of the coils during the forming operation. Another feature of the present invention is the fact that the coils may be wound to exact shapes and than be processed to bind the wire strands together, without requiring any supplementary blocking or forming operations.

Thus the deflection yoke assembly of my invention lends itself to cflicient, low-cost production methods and is superior electrically and mechanically to prior art structures.

It is, therefore, another general object of my invention to provide an improved sweep yoke assembly which not only possesses superior electrical and mechanical characteristics, but which can be readily and economically manufactured in production quantities.

For additional objects and advantages, and for a better understanding of my invention, attention is now directed to the following description and accompanying drawings. The features of the invention believed to be novel are particularly pointed out in the appended claims.

Referring to the drawings, Fig. l is a vertical cross-section view through a sweep yoke assembly embodying the invention, showing the manner in which it is closely fitted around the neck of a television picture tube;

Fig. 2 is a sectional end elevation view looking to the right from the section line 2-2 in Fig. 1;

Fig. 3 is a sectional end elevation view illustrating a modification of the construction of Figs. 1 and 2;

Fig. 4 is a perspective view of one-half of the coil form employed for supporting the deflecting coils in the assembly of Fig. 1;

Fig. 5 is a side elevation view, partly in section, of a modification of the sweep yoke assembly of Fig. 1;

Fig. 6 is a perspective view of the two pairs of deflecting coils of the assembly of Fig. 1, showing the manner in which they are interfitted;

Fig. '7 .is a detailed section view through the end of one of the deflecting coils of Fig. 6, along the section line 1-1;

Fig. 8 is a detailed perspective view of a portion of the coils in Fig. 6, illustrating certain features of their interfltting construction;

Fig. 9 is a perspective view of the essential elements of a machine for the coils of the yoke;

Fig. 10 is a partial sectional view, in a generally vertical plane through the winding head of the machine shown in Fig. 9, showing certain internal details of construction;

Fig. 11 is a partial sectional view in a gener-- ally horizontal plane through the winding head in Fig- 9; and

Fig. 12 is an exploded perspective view of the winding head of Fig. 9, showing more clearly the arrangement and construction of certain parts particularly the two-part removable winding arbor insert.

In the various figures of the drawings, corresponding elements have been designated by corresponding reference numerals, to facilitate comparison.

Fig. 1 illustrates the manner in which the sweep yoke assembly is fitted around the neck of a cathode ray picture tube Hl. Tube in may be any one of a number of well-known-iorms, for example, that mown commercially as type 16KP4, having a cylindrical, or slightly tapoi-ed, neck portion ii and a flared bulb portion l2 which supports the sensitive viewing screen (not shown). lfhe tube M may, for example, be one o! the types particularly adapted for use in television receivers in which the maximum angle of deflection of the cathodev ray, as measured iromthe effective center or deflection IS on the central axis M, may be "50 or more. The flared bulb portion l2 may have either straight or curving sides which subtend a somewhat greater solid angle at their junction with the neck portion ll, represented by the angle 26.

The sweep yoke assembly comprises two pairs of magnetic deflecting coils arranged to deflect the cathode ray, when energized, in two mutually perpendicular transverse planes through the tube ems ll. The resultant field vector direction and strength determines the terminal trace of the ray upon the screen. In accordance with my invention, these horizontal and vertical deflecting coils are saddle-shaped" with their straight sides interlocked so as to form a substantially complete, thin-walled, hollow cylinder, and their outwardly-bent curved ends closely overlying each other. The construction and arrangement of the coils is best seen in the perspective view of Fig. 6, wherein are shown a pair of horizontal deflecting coils l5 and Ii and a pair of vertical deflecting coils Ill and II. It will be observed that each coilhas a pair of straight sides, in which all conductors are parallel to the common axis M.

An important feature of the present invention is the fact that the effective lengths of the coil sides in each pair of deflecting coils are all subthe same. lit is these straight portions of the coils which provide the major part of the total useful transverse magnetic fields for deflecting the ray. As is more clearly evident in the cross-sectional view of Fig. 2, each of these coil sides is curved in the transverse direction so as to lie as closely as possible along the surface of the neck portion H of the cathode ray tube. All coil sides are of substantially uniform radial thickness, and each horizontal coil side subtends an angle of arc, which is just slightly less than of the total circumference, whereas the complementary'vertical coil edge subtends slightly more than ,4; of the total circumference. The outside edges of each pair of coil sides furthermore subtend of arc. By virtue of these constructional features, the two pairs of deflecting coils produce substantially equal magnetic fields for the same number of ampere turns excitation. All of the coil conductors are alsolocatedasclosetothesurfaceof theneck portion H of the cathode ray tube as is physically possible, giving maximum efiiciency.

Referring again to Fig. 6, it will be observed that the ends of the horizontal deflecting coils l5 and Ii lie outside of the ends of the vertical deflecting coils fl and I8. Another imp rtant ieafmre of my invention, which contributes very largely to the efliciency and economy of the system, is the manner in which the adjoining surfaces of the two pairs of coil ends are interfitted to provide minimum waste space and also to permit the entire assembly to be mounted as far forward on the neck portion of the cathode ray tube as posible. The cross-sectional shape of each vertical coil end, at the center of the coil, is as shown in the fragmentary sectional view of Fig. 7. It will be seen that the inner face IQ of this end section is substantially perpendicular to the axis of the coil, while its outer face a is mcllned at an angle of tely 45 to the axis. This acute angle should be approximately the same as the flare angle of the bulb portion I! of the cathode ray tube.

Referring now again to Fig. 1, it will be seen that the cross-section of each horizontal deflecting coil I5, It, at its center, is also wedge-shaped. However, the outer surface ll of the coil end has a somewhat steeper angle of inclination to the tube axis at this point (which lies in the vertical plane passing between the two vertical deflectin coils). The inner surface it has an angle of inclination substantially q l to the flare angle 0 of the tube envelope. As previously mentioned, this permits the entire deflecting yoke assembly to be positioned as far forward against the flared bulb portion II as is physically possible, and yet retain the core length of the assembly shown in my Patent 2,428,947.

The manner in which adjacent surfaces of the crossing end portions of the horizontal and vertical deflecting coils are inter-fitted is illustrated more clearly in the fragmentary perspective view of Fig. 8, which shows the left-hand ends of the coils l and i1 slightly separated from each other. In the vertical deflecting coil II, the outer surface 2|! is continued at substantially the same angle of inclination to the axis over a portion of the area opposite the end of the straight side of the coil. In order for all of the conductors to make the turn at the corner of the coil within the restricted' space available, it is necessary that another portion of this surface, opposite the end of the straight side and in contact with the overlying surface of horizontal deflecting coil l5, be inclined at a somewhat steeper angle to the axis. This transition occurs close to the corner 33 in Fig. 8. correspondingly, it is necessary to form the corner of the horizontal coil II with an indentation, represented at 32 in Fig. 8, which permits the two coils to be interfltted with substantially no lost space whatsoever at their corners. Only in this way is it possible to have the ends of the pairs of coils overlie each other and still provide straight sides of the pairs of coils which are of substantially equal axial lengths.

The interlocking pairs of coils are retained in desired angular and axial positions by means of a two-part coil form having a cylindrical portion 34 closely surrounding the straight sides of the coils and a. pair of annular flanges l5 and 36 which flt snugly between the inner surfaces I! of the vertical deflecting coils. One-half of this coil form, or spool, is shown in perspmtive in Pig. 4. The two halves of the form are interlocked against relative axial movement by means of a pair of lugs 31 on each half of the form which are arranged to engage complementary slots 38 in the other half.

The two halves of the coil form are preferably identical and each molded integrally from a suitable plastic insulating material. The wall thicknesses shoud be as small as possible, consistent with the required mechanical stiffness. Some additional stiflening of the cylindrical portion 34 is also provided by means of thinlongitudinal ribs 39. These ribs also extend radially inward from the inner surface of the form by distances just sufficient to engage the outer edges of the deflecting coil sides. The ribs II, therefore, perform the important function of accurately indexing the angular positions of the deflecting coils with respect to the form.

In order to complete the magnetic circuits for 8 the deflecting coils, a cylinder of ferro-magnetlc material of suitable thickness is placed around the outside surface of the cylindrical portion 34 of the coil form. This may be of a number of known forms of construction. For example as represented in Figs. 1 and 2, the magnetic circuit comprises a split cylinder v4|] composed, for example, of finely-divided powdered iron in a suitable plastic binder or a ferrite magnetic material. The two halves of the magnetic core are retained in position in any suitable manner, as by taping,

or by wrappin a soft iron wire around them and twisting its ends together, Fig. 2.

An alternative construction of the magnetic core is represented in Fig. 3. In this construction the magnetic circuit is composed of a thin sheet of magnetic material formed into a flat spiral having a plurality of turns. This spiral strip is represented at 42 in Fig. 3. As shown, the coil form may conveniently be provided with longitudinal grooves on the outer surface thereof opposite each of the ribs 39. One of these grooves 43 then forms a. convenient anchor for one end of the spiral strip 42 as it is wound on the form.

The flange 35 of the coil form may be of greater radial depth than the flange 36, as illustrated. As shown in Fig. 1, this flange is arranged to abut against a corresponding flange on a cylindrical metal shield can 5|! on one side thereof, and is also arranged to have an annular terminal board 5| positioned against the other face thereof. The whole assembly may then conveniently be fastened together by means of a pair of rivets II.

as represented in The two pairs of deflecting coils may be suit-- ably taped together and to the coil form as required. However, due to their interlocking construction, a minimum of taping is generally necessary. To provide adequate electrical insulation between the pairs of coils, they are preferably separated by thin cone-shaped rings of plastic insulating material, represented at 53 and 54 in Fig. 1. In some cases, it may be necessary or desirable to move the eflfective center of magnetic deflection (represented at point I3 .in Fig. 1) slightly further forward through the use of a magnetic shunt of the general type disclosed in my prior Patent 2,494,459, issued January 10, 1950. This shunt is in the form of a magnetic ring 55 adapted to be placed against the rear ends of the deflecting coils. As shown in Fig. 1, for greatest effectiveness this shunting ring is of frusto-conical shape so as to flt closely against the ends of the coils. It is also preferably insulated from the 00118 by a thin frusto-conical ring 55 of insulating material. This shunting ring effectively weakens the rear fringe of the magnetic deflecting flelds otherwise passing through the tube 'neck, thereby moving the effective center of deflection ll forward. Of course, this is achieved at some sacrifice in efliciency, since greater driving power will then be required in order to scan the same picture area.

Fig. 5 is a partial sectional view of a slightly modified form of yoke assembly which permits the external shielding can 50 to be eliminated. In this case the plastic coil form 51 differs from that previously described in that it is provided with cylindrical extensions 58 and 59 which protect the end turns of the coils and serve the same mechanical purpose as the shielding can 50.

i As a further modification, the coil form or spool may be eliminated completely and the coils may be indexed by means of longitudinal ribs formed 1 on the inner surface of the cy magnetic core ll. In this arrangement, adequate coil insulation must obviously be provided. An external shielding can or other protective enclosure is desirable in this case.

An important feature of my improved deflecting coil construction is the manner in which it lends itself to economical mass production methods with aminimum number ofstepsrequiredin .the manufacturing processtoinsurehighprecision and uniformity in the coil shapes. A preferred apparatus and method for making the deflecting coils of the sweep yoke assembly will now be described in connection with Figs. 9-12 of the drawings.

Thecoilwindingmachinetedinligs. 9-12 operates on the general principles set forth in Patent 2,448,672, issued September '1, 1948, to Harry V. Knauf, Jr. In accordance with the teachings of that patent, the coil is wound upon an arbor which comprises two pieces which are removably attached together and so shaped as to define a winding slot between them of the precise configuration desired for the coil. This winding arbor is supported for rotation about an axis perpendicular to the straight sides of thecoilandthestrandofwireisdirectedalternately to the right and left so as to enter the winding slot as the arbor revolves, by means of radial butterfly vanes."

An improved winding machine operating on these general principles is represented in simplifled form in the perspective view of Fig. 9. It comprises a drive shaft ll. suitably supported in bearings II and 12, which is rotated in any suitable manner. as by means of a pulley l3 and belt 14 driven from an electric motor or other source of motive power (not shown). A revolution counter 15 may be geared to the shaft I. to enable the machine operator to determine the proper number of turns for the coil.

The shaft II has a hub Ii afllxed to it near one end in any suitable manner, as by means of a setscrew 'l'l. sectional views of Figs. and 11 and in the exploded perspective view of Fig. 12, the hub 16 supports the lefthand section II of the winding head. This is cast or fabricated out of aluminum, brass. or other suitable metal and resemblm a wheel having a pair of diametrically-opposite spokes or ribs 19 and I. supporting an outer circular rim 8|. The rim II is also additionally supported by means of a pair of angularly-disposed ribs I2 and 83 which may conveniently be cast as an integral part of the end section II.

As best' seen in Fig. 12. the central portion of the winding head section II is cut away to form a socket adapted to receive a removable, two-part winding arbor ll, IS. The two sectirms of the winding arbor are and have complementary, interfltting surfaces so that when they are clamped together by means of a hollow bolt 86 and nut 81, they define a saddle-shaped winding slot therebetween of the precise configuration of the coil to be wound. For purposes of illustration, the winding arbor shown in Figs.

10-12 is represented as having the configuration necessary for winding the horizontal deflecting coils I5 and". However, it will be understood that the removable arbor for winding the vertical deflecting coils may be constructed in substantially the same manner, differing only in the eonfiguration of thewindingslot.

After the two portions II and 85 of the windingarborhavebeensecnred,itismserted into the socket on the section 18 of the winding head. A pair of coil conductor anchor posts ll and 89, aflixed to the left-hand section ll of the arbor, are provided with spring clips to hold the start and finish leads. An of!- center pin BI is also provided adjacent the hub which engages a hole 91 drilled in section 8| of the arbor in order to prevent its being inserted 180 from the proper angular position. when the winding arbor, has been properly inserted into the socket, the outer edges of the left-hand section 84 form a smooth continuation of th surfaces of the ribs 13 and 80. It will be observed that these ribs are of non-uniform crosssection, having relatively large cross sections hear the hub and tapering down toward the rim so as to form curved, inclined surfaces diverging from the plane of the coil axis in the axial direction. As will appear more fully in a moment, these ribs, and also the ribs 82 and 83, comprise "butterfly vanes which are part of the means for deflecting the wire as smoothly as possible into the winding slot during the winding operation.

The right-hand portion MD of the winding head is somewhat similar to the left-hand portion ll. It has a hub I01 having a rolleror ball-bearing assembly 102 carried in a socket therein. Bearing assembly 102 is freely mounted for rotation on a stub shaft 103 which is axially aligned with shaft 10. As best seen in Fig. 10, a nut 104 is secured to the threaded end of shaft I03 and the hub H is restrained against axial movement with respect to shaft II: by being loosely clamped between this nut and a flange 105 on the shaft. It is, however, free to rotate with respect to the shaft.

As best seen in Fig. 9, the stub shaft I03 projects from a rectangular bar "It which is slidably mounted in a fixed bracket ill! for axial movement. The bar It is arranged to be actuated axially by any suitable lever arrangement (not shown) so that the two halves l8 and ill of the winding head may readily be moved apart to facilitate the insertion and removal of the winding arbor 84, 85.

The right-hand section Hill of the winding head is similar to the left-hand sect on in that it is also generally in the shape of a wheel, having in this case two pairs of parallel transverse spokm III, I and H2, H3, aflixed to the hub Ill and supportin an outer circular rim ill. The hub III also has a transverse, semi-cylindrical, cutaway portion forming a socket for the right-hand face of the winding arbor. As best seen in Fig. 10, a small off-center pin 5 is arranged to engage a socket H6 in the arbor section 85, in order to insure that. the section I ll of the winding head can only be inserted in one angular position.

It willbe observed that the spokes lid-H3 also form inclined vane surfaces for guidin the wire into winding slot and that they are likewise curved so as to diverge axially from the plane of the coil as it is being wound. I

When the winding arbor 88, is properl assembled and clamped between the two portions II, III of the winding head, as represented in Fig. 9, the coil is ready to be wound. Wire is drawn off a supply reel 120, through a tension device comprising a fiat leaf spring 121 secured to a suitable support 122. The operator first passes the wire between the two sections of the winding head and around the spoke 8U, hooking the and under a flat leaf spring on the anchor post I. The winding head is now rotated in a clockwise direction, as viewed in Fig. 9, and the wire is alternately directed to the right and left by the inclined vane surfaces of the spokes so as to seat firmly within the winding space between the halves l4 and 85 of the arbor. By properly determining .the curvatures of the inclined vanes, and adjusting the tension device, stresses on the wire can be maintained sufliciently low so that the head may be rotated at relatively high speed without wire breakage. I have found in actual practice that winding speeds of from 900 to over 2000 revolutions per minute may be employed. The leaf sprin l2! flexes so as to compensate for the pulsating ull on the wire and maintains it under suificient tension to seat snugly into the winding slot.

After the required number of turns have been wound on the coil, the operator hooks the wire under a leaf spring on the projection 88 and breaks the wire at a point above the tension device 2l. The right-hand section Hill of the winding head is now moved to the right, so that the assembled arbor 8H! and the coil thereon may be readily removed as a unit. Another assembled arbor may then be inserted and clamped in the machine and the winding operation repeated.

In a preferred method of manufacturing the coils, the insulated wire is first pre-coated with a thermosetting plastic resin compound. After it is wound on the machine, as previously described, the entire arbor 84, 85 is removed from the machine, the ends of the coil being firmly held by the spring clips on the ends of the pro- .iections 88 and IS. The arbor and coil are then baked in an oven at a moderate temperature and for a sufllcient length of time to fuse the coating. After cooling, the two halves of the arbor are taken apart and the coil removed. This method has been found to produce a very satisfactory coil which is sufllciently rigid to be selfsupporting, eliminating extensive taping to hold the conductors together. It has been previously noted that the straight coll sides are curved in the transverse direction so as to conform to the cylindrical shape of the neck portion of the cathode ray tube. This imparts additional stiffness to the assembled coil and eliminates sidewise bowing, which has previously required additional die blocking operations. As pointed out above, the elimination of such blocking operations practically eliminates the danger of damaging the coil conductors and insulation after winding, as well as saving time and lowering manufacturing costs.

While certain specific embodiments of my improved wide angle sweep yoke assembly have been shown and described, as well as a preferred machine and method for 'winding and forming the coils thereof, it will, of course, be understood that various other modifications may be made without departing from the invention. The appended claims are, therefore, intended to cover any such modifications within the true spirit and scope of the invention.

What I claim as new and desire to secure by letters Patent of the United States is:

1. A wide-angle sweep yoke assembly adapted to be closely fitted around the neck portion of a cathode ray tube with one end closely abutted against the end of the flared bulb portion, comprising two pairs of transverse deflecting coils, each coil having a symmetrical pair of thin, linear coil sides arranged to extend lengthwise along the surface of said neck portion and a pair of 10 outwardly-bent, curved coil ends, said coil sides each subtending substantially 180 degrees of are and being interlocked to form a substantially complete, hollow cylinder, all said coil sides having very nearly the same effective lengths, the coil ends of one pair of coils overlying the ends of the other pair and having complementary, interfitting, inclined surfaces so shaped that there is substantially a minimum of waste space between said surfaces in any radial section plane through the axis of symmetry of saidassembly, the angle of inclination of said interfltting surfaces with respect to said axis diifering substantially from 90 in any such section plane, and the inner surfaces of the outer pairs of coil ends being conically flared to conform substantially to the flare angle between said neck and bulb portions.

2. A wide-angle sweep yoke assembly adapted to be closely fitted around the neck portion of a cathode ray tube with One end closely abutted against the end of the flared bulb portion, comprising two pairs of transverse deflecting coils, each coil having a symmetrical pair of thin, linear coil sides arranged to extend lengthwise along the surface of said neck portion and a pair of outwardly-bent, curved coil ends, said coil sides each subtending substantially 180 degrees of arc and being interlocked to form a substantially complete, thin-walled cylinder, all said coil sid s hav ing substantially the same thickness and e ective length and having complementary edge widths, the coil ends of one pair of coils overlying the ends of the other pair, all crossing portions of adjacent coil ends having complementary, interfitting, inclined surfaces closely contiguous to each other, the angle of inclination of said interfitting surfaces differing substantially from with respect to the axis of said cylinder in any radial section plane therethrough, and the inner surfaces of at least one of the outer pairs of coil ends being flared to conform substantially to the shape of said flared bulb portion near its junction with said neck portion.

3. A wide-angle sweep yoke assembly adapted to be closely fitted around the neck portion of a cathode ray tube with one end closely abutted against the end of the flared bulb portion comprising two pairs of transverse deflecting coils, each coil having a symmetrical pair of thin, linear coil sides arranged to extend lengthwise along the surface of said neck portion and a pair of outwardly-bent, curved coil ends, said coil sides each subtending very nearly degrees of arc and being interlocked so as to lie contiguous to said neck portion when positioned on said tube, all said sides having substantially the same thickness and effective length and having complementary edge widths, and a coil form having a cylindrical body portion closely surrounding said coils, said body portion having four, symmetrically spaced, thin-walled longitudinal ribs on the inner surface thereof, said ribs lying between each adjacent pair of coil sides and positively determining the angular coil positions, said form also having a pair of transverse, annular, end portions, the coil ends of one pair overlying the ends of the other pair, all crossing portions of adjacent coil ends having complementary, interfitting surfaces substantially in contact with each other over at least a major portion of their area of crossing. the angle of inclination of said in-terfltting surfaces diifering substantially from 90 with respect to the axis of said cylinder in any radial section plane therethrough, the outer surfaces of both of the inner pairs of coil ends being in close contact 11' with the end portions of said coil form to prevent relative axial displacement of said coils, and the inner surfaces of at least one of the outer pairs of coil ends being conically flared to conform substantially to the shape of said flared bulb portion near its junction with said neck portion.

4. A wide-angle sweep yoke assembly adapted to be closely fitted around the cylindrical neck portion of a cathode ray tube with one end closely abutted against the end of the flared bulb portion, comprising two pairs of transverse deflecting coils, each coil having a symmetrical pair of thin, linear coil sides arranged to lie closely contiguous to said neck portion and a symmetrical pair of outwardly-bent, curved coil ends, said coil sides each subtending substantially 180 degrees of arc and being interlocked to form a thin-walled cylinder, all said coil sides being of substantially uniform thickness and having substantially the same effective lengths and complementary edge widths, the coil ends of one pair of coils lying outside of the ends of the other pair, all crossing surfaces of adjacent coil ends being interfltted so as to hem substantially continuous physical contact with each other, said crossing surfaces being inclined at an angle differing substantially from 90 with respect to the axis of said cylinder in any radial section plane therethrough, and the inner surfaces of both pairs of outside coil ends being conlcally flared to conform substantially to the shape of said flared bulb portion near its junction with said neck portion.

5. A wide-angle sweep yoke assembly adapted to be closely fitted around the cylindrical neck portion of a cathode ray tube with one end closely abutted against the end of the flared bulb portion, comprising a first pair of symmetrical, vertical deflecting coils each having a pair of straight sides arranged to lie contiguous to the surface of said neck portion parallel to a common axis of symmetry and also having a pair of transverse curved ends, said coils being arranged to surround opposite halves of said neck portion, a second pair 01' similar, symmetrical, horizontal deflecting coils interlocked with said vertical coils, the straight sides of all said coils having substantially the same length and radial thickness and having complementary edge widths, the ends of one pair of coils lying outside and crossing over those of the other pair, the inner pairs of coil ends havin their outer surfaces lying in planes transverse to said axis and their inner surf-aces inclined at angles differing substantially from to said axis, the angle of inclination at the center of each said inner end being approximately equal to the flare angle between said neck and bulb portions of said tube, the outer pairs of coil ends having their outer surfaces conforming closely to the shape of said inner surfaces and in physical contact therewith over at least a major portion of their area of crossing, the inner surfaces of said outer pairs of coil ends also being inclined to said axis at said flare angle, a cylindrical insulating spool closely surrounding said straight sides and having its ends abutting said outer surfaces of the inner coil ends, and a cylindrical magnetic circuit element surrounding said spool.

CHARLES E. TORSCH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,108,523 Bowman-Manifold Feb. 15, 1938 2,236,498 Blain Apr. 1, 1941 2,240,606 Bobb May 6, 1941 2,333,806 Mauerer Nov. 9, 1943 2,395,736 Grundmann Feb. 26, 1946 2,428,497 Torsch Oct. 14, 1947 

